Interaction of landfill leachate with olivine-treated marine clay: Suitability for bottom liner application

The interaction between landfill leachate and olivine-treated marine clay was studied to assess its chemical compatibility for suitable application as a bottom liner material in engineered landfills. Soil specimens were prepared using three compactive energies (reduced, standard, and modified Proctors) at -2, 0, +2, and +4% moisture contents of the optimum moisture content and treated with up to 35% olivine content. Index properties, volumetric shrinkage strain (VSS), unconfined compressive strength (UCS), and hydraulic conductivity (HC) tests were conducted. Overall acceptable moisture content range for which the specimens are apt as a bottom liner material was obtained. Test results demonstrate improvement in the UCS, HC, and VSS with increasing olivine content up to 30% olivine content when all three compactive efforts were employed. Formation of magnesium aluminate hydrate (M-A-H) and magnesium silicate hydrate (M-S-H) were the key components responsible for this hydro-mechanical properties improvement and were confirmed using morphological and mineralogical analyses. Based on the obtained overall acceptable moisture content range, all olivine-treated samples met the required specifications over a range of moisture content varying between 9.5 and 20.9% depending on the compactive efforts. These findings indicate that compacted marine clay treated with up to 35% olivine content can be utilized as a potential barrier material in engineered landfills with optimum results at 30% olivine content.